A device of the aforementioned type is disclosed in DE 197 42 559 C2 issued to the applicant of the present patent application. In the known device, the second receptacle containing the substance is formed by a tubular insert that is inserted into the neck of the first receptacle, which is shaped in the form of a bottle. A groove with a predetermined breaking point is formed on the bottom of the insert, so that the bottom can be broken or swung open by the action of a force, so that the substance falls into the liquid of the first receptacle. The bottom is opened by the front part of an airless pump which is displaceably arranged in the insert. When the airless pump is advanced in the longitudinal direction of the first receptacle, i.e. pushed into the receptacle, it breaks open the bottom of the insert.
In this known configuration the problem arises that, while the pump means is being pushed forwards or slid in, air is pressed into the suction area of the pump, which may lead to malfunctions during initial pumping of the liquid. If, in addition, as is the case with some applications e.g. in the medical or pharmaceutical or also hygienic sector, the contents of the receptacle is to remain sterile, this cannot be guaranteed with the prior-art device because the air pressed into the interior of the receptacle upon the advance movement of the pump may be contaminated.
U.S. Pat. No. 6,230,884 B1 discloses a receptacle cap with a blister pack which is opened by depressing a neck section of the cap, wherein a pin-like attachment presses a tablet out of the blister pack, with the tablet falling into the liquid contained in a bottle. Ambient air may here enter unimpededly into the bottle.
U.S. Pat. No. 4,770,323 deals with the problem to provide a sterile packaging for a fluid that is hermetically sealed by a breakable sealing membrane until the first discharge, wherein after the sealing membrane has been broken open an unhindered discharge of the receptacle contents is to be made possible for a long period of time. To this end a tubular perforation element is pressed through the sealing membrane and gets into engagement with a small rising tube in the receptacle, with the small rising tube being connected to a discharge channel that extends through the cap of the packaging. With this kind of packaging, air can also enter into the packaging after the sealing membrane has been broken open.